Method of making a hollow mold



NOW 24, 1964 G. H. BINGHAM, JR 3,153,553

METHOD OF MAKING A HOLLOW MOLD Filed Jan. 255, 1962 2 Sheets-Sheet 1INVENTOR. GEORGE H. BINGHAM JR.

ATTORNEYS Nov. 24, 1964 G. H. BINGHAM, JR

METHOD OF MAKING A HOLLOW MOLD Filed Jan. 25, 1962 2 Sheets-Sheet 2INVENTOR. GEORGE. H. BINGHAM JR.

ATTORNEYS United States Patent 3,158,558 METHUD 0F MAKEWG A HGLLUW MQLDGeorge H. Binghain, fin, Westminster, Md assignor to Cambridge RubberCompany, 'ianeytewn, Paid a corporatien of Maryland Filed Jan. 23, M62,Ser. No. 16$,ltlil 3 Claims. (Cl. 2G4-8) This invention pertains to themanufacture of plastic boots by the slush-molding process, moreparticularly to a mold for use in making a boot whose upper isexternally ornamented with widely distributed relief designs which maybe in color; to a method of making such a mold; and to a boot made bythe use of such a mold.

In accordance with a method more fully described in the copendingapplication for United States Letters Patent, Serial No. 167,389, filedJanuary 19, 1962, by George H. Bingham, In, now abandoned, there isdescribed a procedure whereby it is readily possible to provide anarticle of footwear, for instance a boot, with simple external ornamentsin relief, the elements of ornament being integrally united to thematerial constituting the wall proper of the article, and, if desired,being of a material different from that of the boot proper, or of acolor or colors contrasting with that of the boot proper.

While the method described in the aforesaid application is useful andpractical for the application of ornamental designs of limited extent,it is not wholly acceptable for the application of designs which extendover wide areas of the periphery of the boot leg since, in accordancewith that method, and, in particular, when the designs involve theemployment of contrasting colors, the method involves the step offlowing a fluid into cavities or along grooves or channels formed at theinterior of the mold. Because, at almost every transverse section, theleg of the conventional boot, and thus the mold, is curved, the cavitiesor channels in the mold may not be confined to the same plane, and thusgreat skill is required in tilting the mold, in one direction oranother, to cause the fluid to flow throughout the entire pattern areawithout overflowing the cavities or channels at some point and thusfouling the adjacent area of the boot.

The present invention has for an object the provision of a mold wherebyit is made possible to flow a fluid, for example coloring material,without danger of overfor example coloring mtaerial, without danger ofoverflow, into channels or cavities forming designs which cover verysubstantial areas of the boot top. A further object is to provideappliances useful in the practice of the invention. A further object isto provide a moistureimpervious boot having extended areas of its outersurface ornamented by designs, in relief and/ or in color.

In the attainment of the above objects, the invention comprises the stepof so deforming the basic boot, which is used in the preparation of amodel for use in making a mold, that those areas to which theornamentations are to be applied become approximately fiat. For thispurpose, there is provided what may be termed a last (or more correctlya plug, since it would not ordinarily comprise a part shaped to the footportion of the boot), which is substantially rectangular in transvresehorizontal section and which is of such dimensions that, when forceddown into the upper of the basic boot which is to be used in preparingthe model, it stretches the upper of the boot in the front-to-reardirection while narrowing it transversely, so that the opposite sides ofthe boot upper are approximately flat and, likewise, the front and rearsurfaces of the upper may be also approximately fiat, although narrowerthan the sides.

Having introduced such a last or plug into the basic boot, the selectedelements of ornaments are then appliqued to these approximately flatsurfaces of the boot and 3,158,558 Patented Nov. 24, 1964 ice firmlysecured in place as by adhesive or otherwise. Then the model orprototype thus prepared is electroplated for the formation of a hollowmold for use in manufac turing the desired boots.

By the above procedure it is possible to decorate substantially theentire side surface of the boot top with elaborate ornamentation, andlikewise, if desired, to provide the front and rear of the boot withall-over ornamentation. While the resultant boot, after molding, appearsunusually narrow, transversely, its peripheral extent, nevertheless, isas great as that of the basic boot which was used in preparing themodel. However, the boot upper is flexible and thus, in donning theboot, it is merely necessary to stretch it transversely to bring it backto the customary shape for the reception of the foot and leg, and whenit is on the foot it readily conforms to the foot and leg so that itdoes not appear substantially different from the ordinary boot, exceptfor the fact that it has a highly ornamental appearance.

In the accompanying drawings:

FIG. 1 is a perspective view showing a boot having such extendedornamentation in relief form;

FIG. 2 is a section substantially on the line 2-2 of PEG. 1, showing thegeneral shape of the boot when off of the foot;

FIG. 3 is a diagrammatic perspective view illustrating the generalappearance of a basic boot, substantially devoid of ornamentation, butwhich, in practice would be of the same general style and size at thatof the boot of FIG. 1, and which may be employed in the preparation of amodel or prototype boot useful in the making of a mold for use in themanufacture of a boot like that of FIG. 1;

FIG. 4 is a perspective view of a last or plug useful in temporarilydeforming the boot of FIG. 3;

FIG. 4a is a section on the line 4a4a of FIG. 4;

FIG. 5 is a diagrammatic, perspective view of the basic boot of FIG. 3,with the plug within it, showing the boot stretched from front-to-rearwhile narrowed transversely and, by way of example, showing very simpleelements of ornament as having been attached to a side area and front ofthe leg of the basic boot which has been deformed by the introduction ofthe plug to lie substantially in a plane;

FIG. 6 is a diagrammatic section on a plane such as indicated by theline 66 of FIG. 5, showing the plug within the basic boot and havingelements of ornament attached to each of its flattened faces, thusconstituting a model for use in making a mold; the thickness of the wallof the boot being exaggerated relatively to the transverse dimensions ofthe boot;

FIG. 7 is a section like that of FIG. 5, but showing the model as havingbeen electroplated to form a thin metal shell useful, after removal ofthe model, as a mold in the slush-molding of ornamented boots and FIG. 8is a transverse section showing the hollow shell of FIG. 7, in readinessfor use as a mold in the manufacture of boots having simple externalrelief ornamentation. It will be observed that this hollow mold hascavities or channels in its inner surface corresponding in location tothe location of the elements of ornamentation illustrated in FIGS. 5 and6, these cavities or channels being replicas, but in reverse, of saidelements, and in each instance, extending over a substantially flat areaof the wall of the mold.

When herein reference is made to a boot, that term is not to beconsidered as limiting, since the present method of preparing a mold maybe employed in making molds for use in the manufacture of other articlesof footwear, other wearing apparel or, in fact, in general, flexiblearticles made by the slush molding operation, wherein the surface towhich the ornamentation is to be rear.

i) applied is normally curved such that the operation of applying color,in providing an extended area of ornamentation, would ordinarily bedifficult.

Moreover, when the term element of ornament is herein employed, suchexpression is, intended to include not only independent or isolatedshapes, but also component portions of more-or-less complex figures.

Referring to FIGS. 1 and 2 of the drawings, the character B indicates aboot or bootee primarily intended for childrens wear and made, forexample, by the slushmolding process from a suitable plastisol 2 asindicated in the section in FIG. 2. This boot, as shown, has the legportion 21 and the foot portion 22, being, in fact, conventional exceptfor the fact that it has extended areas of ornamentation (FIG. 2) on itsright and/ or left sides as indicated in general, at T and likewise, ifdesired, extended areas of ornamentation T at its front and/or its Aswill be noted from inspection of FIG. 1, the ornamentation is in reliefand, as shown, is a decoration of pleasing but complex charactercovering almost the entire outer surface of the leg of the boot. Whilethe ornamentation may be of the same material and/ or color as theplastisol of which the boot proper is made, it is possible, inaccordance with the present invention, to make it of another material orcolor. No attempt to indicate color is here made.

As shown, the boot has other elements of ornamentation of more-or-lessconventional type, such as the binding strip 23 at the top of the boot;an ornamental strip 24 at the toe, suggestive of a toe cap; a strip 25at the U quarter portion, suggesting a heel stifiener; and a strip 26 atthe forepart, suggestive of the upper edge of a vamp. Likewise, there isa strip 2'7 extending around the periphery of the boot at its bottom andrepresenting a foxing. However, these latter elements of ornamentation(although they may be provided for in the same mold as the otherornamental features) are not essential with respect to thepresentinvention.

In preparing a mold for use in the manufacture of boots, such as thatshown in FIG. 1, the general procedure may be similar to that describedin the aforesaid copending application, comprising the first step ofselecting a basic boot Bx (MG. 3) of the general style and size of theboot B (FlG. l) which is to be manufactured by the use of the mold to beprepared in accordance with the present invention. The boot Ex isdesirably one which has a simple, that is to say, substantially plainouter surface devoid of ornamentation such as might interfere with thatwhich is to be applied.

There is then provided a last or plug P (Phil. 4) which may, forexample, be of wood or of some light metal such as an aluminum ormagnesium alloy and which is substantially rectangular in horizontaltransverse section, having the substantially parallel fiat side faces orsurfaces 27 and 28 and the substantially plain front and rear edge faces29 and 30. However, the plug preferably has rounded corners of shortradius, as shown at 31, where the side and front faces are joinedtogether. If this plug be made of metal, it is preferable to make ithollow, as shown in FIGS. 4 and 4a, so as to reduce the weight. As shownin FIG. 4, it may be tapered more-orless from front-to-rear so that itsrear face 30 will follow the contour of the rear part of the basic bootwhen introduced into the leg of the boot. The plug is of such dimensionthat when pushed down into the leg of the basic boot, as shown in FIG.5, it stretches the boottop from front-to-rear while narrowing ittransversely.

Desirably, the peripheral extent of the plug is slightly greater thanthe inner periphery of the basic boot Bx, so that when the plug ispushed down into the boot, the boot-top is stretched slightly so as toplace the material under tension. Because of the shape of the plug, theside surfaces of the boot top are now substantially flat and paralleland, likewise, its front and rear edge surfaces. Having thus deformedthe boot Bx, as shown at Bin (FIG. 5), by the introduction of the plugP, elements of ornament Tm may now be appliqued as, for example, by useof adhesive to the exposed approximately flat side surfaces of the bootand, if desired, to its front and rear faces, as indicated at Tn. Theelements thus applied to the boot top may be prepared in any desiredmanner from material of approximately the thickness of the desiredrelief pattern on the completed boot. Such elements of ornament maycomprise pieces of plain sheet material; embossed material; materialproduced by a molding operation; narrow ribbons or strips cut from sheetmaterial, or in fact any desired objects, and may be combined, inapplying them to the surfaces of the boot, so as to form complex and/ orextended designs, but, in applying said elements, confining theornamentation to areas of the boot which are substantially flat. Forsimplification in illustration, but without limitation, the elements ofornament shown in FlGS. 5 and 6 are of the simplest.

Having prepared the model boot Bm illustrated in FIGS. 5 and 6, byattaching elements of ornament to the flattened basic boot, theresultant model is electroplated according to any desired orconventional procedure to form the metallic shell 32, shown in FIG. 7.After a shell of the desired thickness has been built up upon the mold,the model Bm is removed, thus providing the hollow mold 32m (FIG. 8).The mold, as shown, is substantially rectangular in shape in transversesection and has grooves or channels K and K in its inner surfacecorresponding to the elements of ornament Tm, Tn which were attached tothe deformed basic boot. This mold may now be employed in manufacturingboots such as that of FIG. 1, by the slush-molding operation. If theornament is to be of a material different from or of a color contrastingwith that of the boot proper this involves the introduction of anappropriate material, usually a fluid into the cavities or channels Kand K in the mold.

Since these parts of the mold 32m (FIG. 8) wherein these cavities arelocated are substantially fiat, it is readily possible to introducefluid to fill the grooves or channels K, even though the grooves orchannels may cover a major portion of the interior surface of the mold.For example, the mold, when in the position shown in FIG. 8, may havethe channels K in its lower horizontal wall filled or partially filledwith a fluid, for instance a colored plastisol, and when this has beengelled by heat, it is possible to turn the mold so that another of itsgrooved sides is horizontal and the channels or cavities in that wallfilled or partially filled with colored plastisol and gelled and so onuntil all of the channels have been filled to the desired extent.Thereafter, the mold is turned to upright position and filled with theplastisol which is to form the body of the boot and after pouring offsurplus liquid, the mold is heated so as completely to fuse all of theplastisols which have been introduced, with the result that when theboot is removed from the mold, the relief ornamentation is in a color orcolors contrasting with the color of the plastisol forming the body ofthe boot. For example, the ornamentation may be red while the body ofthe boot is black, or the ornamentation. may be of varied colors, whilethe body of the boot is white.

While one desirable procedure in the preparation of a mold appropriatefor forming a boot such as that of FIG. 1, the characteristics of themold so formed, and a boot made by the use of the mold, have herein beendescribed by way of example; it is to be understood that the method andarticles so described are by way of example and that any and allmodifications falling within the scope of the appended claims, are to beregarded as embraced in the invention.

I claim:

1. That method of preparing a mold to be used in the manufacture, by theslush-molding procedure, of a boot, one side, at least, of whose leg hasan all-over ornamental design, said method comprising as steps:providing a basic boot of approximately the size and shape of the bootto be manufactured by the use of the intended mold but which issubstantially devoid of ornamentation, stretching the leg portion of theboot in the front-t0 rear direction While narrowing it transversely sothat it becomes substantially rectangular in horizontal section, theouter surfaces of the right and left Walls of the boot leg beingsubstantially parallel and fiat, while its front and rear surfaces arenarrower than the side wall surfaces, each of the fiat side surfacesbeing of adequate extent to receive and support an all-over design ofextended area, appliqueing, to at least one or" said flat side surfaces,elements of ornament of selected thickness and which collecetively formthe desired design thus constituting a model boot having, on one sidewall at least, the desired ornamental design in relief, electroplatingthe model boot thus prepared to form a thin metallic shell, and removingthe model boot from the shell thereby producing a hollow metallic moldwhose side Walls are approximately fiat, While the inner surface of atleast one of said side Walls has cavities corresponding in shape, sizeand location to the elements of ornament which were appliqued to thebasic boot.

2. That method of preparing a mold to be employed in the manufacture, bythe lush-molding procedure, of a boot whose leg portion has an all-overdesign covering an extended area of its outer surface, said methodcomprising as steps: providing a basic boot of approximately the sizeand shape of the boot to be manufactured by the use or" the intendedmold but which is substantially devoid of ornamentation, so deformingthe leg portion of said basic boot, by stretching it from front-to-rear,that it becomes substantially rectangular in horizontal section and sothat its opposite side surfaces are substantially parallel and flatwhile its front and rear surfaces are likewise substantially paralleland flat but narrower than the side surfaces, appliqueing to each ofsaid flat surfaces elements of ornament of selected thickness to form adesign on each of said flat surfaces thereby producing a model boothaving fiat surfaces, each covered by a desired ornamental design inrelief-electroplating said model boot to form a thin metallic shell, andremoving the model boot from said shell thus producing a hollow metallicmold whose wall has approximately flat side and front and rear portionsin whose inner surfaces are cavities corresponding in shape, size andlocation to the elements of ornament which were appliqued to the basicboot.

3. The method according to claim 1, further characterized in that forstretching the boot from front-to-rear there is provided a rigid plugwhich in horizontal section is substantially rectangular but narrower,from side-to-side than from front-to-rear, and which is of a sizesubstantially to fill the leg portion of the basic boot when forceddownwardly into the latter and which, when so forced down into the legof the basic boot, deforms the leg portion of the boot so that theperipheral wall of the leg now comprises relatively Wide, substantiallyflat side areas and relatively narrow, substantially flat front and rearareas, appliqueing elements of orament so as to cover and conceal asubstantial extent of a selected one, at least, of said flat areasthereby forming a model boot, employing this model boot in themanufacture of a mold by electroplating the model boot, and subsequentlyWithdrawing the model boot, including the plug, from the metallic shellresultant from electroplating.

References Cited by the Examiner UNITED STATES PATENTS 1,813,880 7/31Kraft 204-6 1,867,881 7/32 Crockett 18-41 2,327,762 8/43 Bull 204-62,540,531 2/51 Johnston 36-4 2,662,308 12/ 53 Loewengart 18-41 2,679,4735/54 Swartz 204-6 2,730,765 1/56 Crafton et a1 18-39 2,838,854 6/58Dosmann 36-4 2,908,040 10/59 Schneider 18-41 2,923,032 2/60 Miller eta1. 18-39 2,949,410 8/60 Bingham 204-9 3,068,156 12/62 Efron 204-9 JOHNH. MACK, Primary Examiner.

WILLIAM J. STEPHENSON, JOHN R. SPECK,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0 3,l58558 November 24 1964 George H, Bingham Jro It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 5 line 39, after "relief" insert a comma Signed and sealed this6th day of April 1965.,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. THAT METHOD OF PREPARING A MOLD TO BE USED IN THE MANUFACTURE, BY THESLUSH-MOLDING PROCEDURE, OF A BOOT, ONE SIDE, AT LEAST, OF WHOSE LEG HASAN ALL-OVER ORNAMENTAL DESIGN, SAID METHOD COMPRISING AS STEPS:PROVIDING A BASIC BOOT OF APPROXIMATELY THE SIZE AND SHAPE OF THE BOOTTO BE MANUFACTURED BY THE USE OF THE INTENDED MOLD BUT WHICH ISSUBSTANTIALLY DEVOID OF ORNAMENTATION, STRETCHING THE LEG PORTION OF THEBOOT IN THE FRONT-TO REAR DIRECTION WHILE NARROWING IT TRANSVERSELY SOTHAT IT BECOMES SUBSTANTIALLY RECTANGULAR IN HORIZONTAL SECTION, THEOUTER SURFACES OF THE RIGHT AND LEFT WALLS OF THE BOOT LEG BEINGSUBSTANTIALLY PARALLEL AND FLAT, WHILE ITS FRONT AND REAR SURFACES ARENARROWER THANT HE SIDE WALL SURFACES, EACH OF THE FLAT SIDE SURFACESBEING OF ADEQUATE EXTENT TO RECEIVE AND SUPPORT AN ALL-OVER DESIGN OFEXTENDED AREA, APPLIQUEING, TO AT LEAST ONE OF SAID FLAT SIDE SURFACES,ELEMENTS OF ORNAMENT OF SELECTED THICKNESS AND WHICH COLLECTIVELY FORMTHE DESIRED DESIGN THUS CONSTITUTING A MODEL BOOT HAVING, ON ONE SIDEWALL AT LEAST, THE DESIRED ORNAMENTAL DESIGN IN RELIEF, ELECTROPLATINGTHE MODEL BOOT THUS PREPARED TO FORM A THIN METALLIC SHELL, AND REMOVINGTHE MODEL BOOT FROM THE SHELL THEREBY PRODUCING A HOLLOW METALLIC MOLDWHOSE SIDE WALLS ARE APPROXIMATELY FLAT, WHILE THE INNER SURFACE OF ATLEAST ONE OF SAID SIDE WALLS HAS CAVITIES CORRESPONDING IN SHAPE, SIZEAND LOCATION TO THE ELEMENTS OF ORNAMENT WHICH WERE APPLIQUED TO THEBASIC BOOT.